Crop production is affected by many factors, and the fertilization conditions are ever-changing. Understanding the fertilizer characteristics and fertilization principles of crops can be done according to local conditions. It is recommended that the fertilization frame be within a reasonable range. The basic principles include other agricultural measures to help farmers' friends to broaden their thinking and comprehensively manage crop production when analyzing and solving practical problems. This article intends to systematically discuss the main crops in China on this topic. Let's talk about rice first.
The growth and development of rice can be divided into seedlings, tillers, booting, heading, flowering, and maturity. The fertilizer characteristics and fertilization principles are:
Fertilizer characteristics
There are two peaks in nutrient absorption. The tillering stage and the panicle differentiation stage of rice are the two peaks of nutrient uptake, but the single-season rice is different from the double-season rice. The growth period of single-season rice is longer, and the peak interval of two fertilizers is distinct, which is the key to topdressing; the growth period of double-season rice is shorter, and the peaks of two fertilizers tend to overlap. Therefore, the center of fertilization is earlier than that of single-season rice, but the amount of fertilizer is relatively small. .
Sensitive to zinc deficiency, susceptible to "shrinking disease". Most of the zinc-deficient soils are calcareous paddy soil, paddy soil in coastal saline soil and paddy soil in low-lying marsh area, especially winter wheat, rice and early rice are more likely to be lacking; excessive application of phosphate fertilizer can also induce zinc deficiency. Adding organic fertilizer and rational application of phosphate fertilizer can prevent zinc deficiency; zinc fertilizer can be used as base fertilizer or foliar spray to correct zinc deficiency.
Rice is a silicon crop. Rice is the crop that absorbs the most silicon. Silicon can promote rice respiration and root growth, improve photosynthesis efficiency, strengthen stems, enhance resistance to lodging and disease resistance, and especially increase potassium and silicon fertilizers for high-yield rice.
The root zone soil has a special oxidation-reduction layer. Rice is grown for a long time under flooding conditions. The soil layer is divided into an oxide layer close to the water body (a few millimeters to 1 cm above the tillage layer ) and a lower reduction layer. The reducing layer is deficient in oxygen. If the nitrate nitrogen fertilizer is applied, in addition to the water leakage, it will become gaseous nitrogen loss under the action of denitrifying microorganisms. Therefore, it is necessary to use or not to use nitrate nitrogen fertilizer.
It is not advisable to use the nitrate nitrogen test method for nutritional diagnosis. When rice is grown under flooding conditions, the absorbed nitrogen is mainly present in the body before the conversion. Therefore, the plant nutrient rapid measurement mainly uses the chlorophyll colorimetric method instead of the nitrate content; under flooding conditions, Soil available nitrogen is also mostly present in ammonium nitrogen, and it is not suitable for nutrient diagnosis by nitrate-based rapid measurement.
The effectiveness of soil nutrients in paddy fields is different from that in dry fields. Under flooding conditions, phosphate fertilizers and iron, manganese and other nutrients are more effective than dry fields, and sometimes even poisonous due to excessive manganese content. Therefore, after the dry land is changed to paddy field, the phosphate fertilizer can be appropriately applied less, and the deficiency of iron and manganese is also alleviated. After the paddy field is changed to dry field, the amount of phosphorus should be appropriately increased, and attention should be paid to the lack of elements such as iron and manganese.
There are special requirements for moisture management. Moisture is an important material for rice plant material composition and photosynthesis. The transpiration of water can regulate plant body temperature, improve growth environment, prevent low temperature freezing damage and inhibit weed growth. The relationship between water status and crop growth is vividly illustrated by the theory of “watering high and low rootsâ€, which has important guiding significance for rice water management and should be applied flexibly according to specific conditions.
Fertilization principle
Improve fertilization techniques. Promote the combination of land preparation, increase the application of organic fertilizer, return straw to the field or plant green manure; control the total amount of nitrogen fertilizer, shift the center of gravity of nitrogen fertilizer, appropriately reduce the proportion of nitrogen fertilizer of base fertilizer and tiller fertilizer, to reduce the early ineffective tillering and prevent post-fertilization; Increase the application of potassium fertilizer, promote base fertilizer, topdressing and fertilizer application; advocate "fertilizer with water" fertilization technology to improve fertilizer and water use efficiency; through reasonable application of nitrogen, potassium, silicon fertilizer and reasonable close planting, water layer management and other comprehensive measures, Control rice lodging and improve disease resistance; appropriate amount of lime can be applied in acid soil rice fields as appropriate.
Scientifically control moisture. Rice has different sensitivities and requirements for water in different growth stages, and it should be well controlled from time to time. In the seedling stage, the shallow water layer or the soil should be kept moist. When the wind is cool, it is necessary to fill the water to protect the seedlings; in the transplanting and returning period, stable temperature and humidity conditions are needed, so it is necessary to maintain a certain water layer so as to “level with water†during the preparation of the ground. After transplanting, the seedlings and seedlings should be planted; after the seedlings are planted, with the increase of tillering, it is necessary to properly drain the fields, inhibit the ineffective tillering and promote the roots; the young panicle differentiation stage and the heading flowering stage are sensitive to water shortage, so that the rice should be made. It is in the alternating state of soil moist and shallow water layer; the grouting period requires neither water accumulation nor early water cut, and intermittent filling can be used to make the paddy field alternate between waterlogging and falling water. This is beneficial to the plant nutrient concentration to the grain, and to prevent premature senescence of the leaves and roots; water is cut off 5 to 10 days before harvest to facilitate the sputum arrangement and field operations.
Strengthen integrated management. At the same time of scientific fertilization and irrigation, it is necessary to select seeds and sow seeds before sowing, and disinfect and germination of seeds. In the greenhouses of Heilongjiang and other places, the rice cultivation should be carried out in a timely and appropriate manner, and the bed surface should be properly dried to carry out "smelting seedlings" and cultivating strong and strong. Before the transplanting, it is necessary to combine deep shovel with shallow shovel to improve the quality of the land preparation and timely transplanting. The height difference of the field surface is generally no more than 3 cm. It is necessary to carry out weeding in the field, focusing on the control of rice blast, sheath blight, bacterial blight and thrips, rice planthoppers, armyworms and so on. Pests and diseases.
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